1. Field of the Invention
This invention relates to moisture indicator strips for diapers, hospital underpads, and the like. More particularly, this invention relates to moisture indicators of the capillary action type which provides a visual indication of wetness at a point removed from the actual point of wetness, such as at the edge of the diaper or surgical dressing. Further, this invention relates to a method for automatically and continuously incorporating a wetness indicator within the structure of the diaper or underpad during the manufacture thereof.
2. Description of Prior Art
Presently there exists many types of wetness indicators for use in conjunction with diapers, surgical dressings, hospital underpads, and the like. Basically, these types of wetness indicators can be classified into three broad categories: those which consist of imprinting a moisture indicating pattern on one of the plies of the diaper or underpad; those which consist of a discrete moisture indicating strip or layer which is incorporated between the layers of the diapers or underpad; and, those which consist of a discrete indicating strip which may be fastened to the interior of the diaper or underpad immediately prior to use.
U.S. Pat. Nos. 3,675,654 and 4,022,211 teach the general concept of imprinting a moisture indicating design onto the translucent moisture impervious outer covering of the diaper or underpad. One obvious advantage to this concept is the fact that the imprinting can be performed continuously during the manufacture of the diaper or underpad. Unfortunately, one major disadvantage to this concept is the fact that the only portion of the imprint which changes color is that which is in direct contact with the moisture. Obviously, such limited indication of wetness is highly undesirable in that the actual area of wetness itself may be obstructed from view. For example, in the case of diapers, it is well-known that only the crotch area of the wearer becomes wet during urination and that, therefore, the color change reflected by the imprint would be limited to the crotch area. If the wearer is dressed in a pair of shorts or trousers, this visual indication of wetness will, indeed, be of little significance in that such would be obstructed from view by the wearer or his/her attendant.
The second broad category of wetness indicators are those which consist of a discrete moisture indicating layer or strip which is incorporated within the plies of the diaper, underpad, or the like. U.S. Pat. Nos. 2,249,867, 3,759,261, 3,918,433, 3,918,454, 3,952,746, 4,192,311, and 4,231,370, and French Patent No. 1,355,018 teach the general concept of the second broad category of moisture indicators. Specifically, each of these patents teach the concept of incorporating a discrete ply(ies) or strip(s) into the diaper. In some embodiments, a single ply or strip is incorporated within the layers of the diaper which is impregnated or treated with various chemical compositions that experience a change in color upon becoming wet by urine or other moisture. In other embodiments, two or more plies are used wherein a first ply is colored or includes other visible indication means and wherein a second ply functions to obscure the view of the first colored ply until the second ply becomes translucent or transparent so as to no longer obscure or hide the first colored ply, thereby allowing the first colored ply to be viewed by the wearer or his/her attendant.
These patents of the second broad category suffer the same disadvantages of the first broad category of wetness indicators in that each of them only provides an indication of wetness at the precise zone of actual wetness, thereby being, in most applications, of marginal value. Further, these discrete moisture indicators cannot be automatically incorporated into the diaper during the manufacture thereof without unduly increasing the cost of manufacture of the diaper. Accordingly, these discrete moisture indicators of the second broad category have not been accepted by the industry.
Finally, the third broad category of moisture indicators consists of a capillary-type moisture indicating strip as taught by U.S. Pat. No. 3,731,685. Basically, this capillary-type moisture indicating strip consists of a strip having one end designed to be exposed to and receive the moisture and the other end impregnated with a chemical which changes color when wetted by the moisture. The strip comprises a wicking material which is capable of supporting capillary action such that moisture is transported from its moisture receiving end to its chemically impregnated end which experiences a change in color when exposed to such moisture. The strip itself is specially designed to be used in conjunction with diapers, surgical dressings, hospital underpads, sanitary napkins, and the like. Experience has shown that this type of capillary action strip works remarkably well to provide an indication of wetness at a point remote from the actual point of wetness, thereby overcoming the common, major disadvantage of those types of wetness indicators of the two broad categories outlined above. However, like the discrete moisture indicators of the second category above, this capillary-type moisture indicator of third category is also a discrete component which, in its present form, also unduly increases the cost of the diaper, underpad, etc. during the manufacture thereof. As a result, this capillary-type moisture indicator has achieved commercial success only by selling it as a separate article of manufacture. In this manner, the consumer has the opportunity to utilize a capillary-type moisture indicating strip in conjunction with any type of diaper, underpad, surgical dressing, et cetera. The disclosure of each of the eleven above identified patents are hereby incorporated by reference herein.
Therefore, it is an object of this invention to provide an apparatus and method which overcomes the aforementioned inadequacies of the prior art devices and provides an improvement which is a significant contribution to the advancement of the moisture indicating art.
Another object of this invention is to provide a capillary-type moisture indicating strip which provides a visual indication of wetness at a point removed from the actual point of wetness to conveniently indicate a condition of wetness when the point of wetness is obscured from view.
Another object of this invention is to provide a capillary-type moisture indicating strip particularly suited for diapers and hospital underpads and the like.
Another object of this invention is to provide a method of incorporating a capillary-type moisture indicating strip into the diaper or underpad during the manufacture thereof without interrupting or reducing the speed of the production of such diaper or underpad.
Another object of this invention is to provide a capillary-type moisture indicating strip which provides a visual indication of wetness at a point removed from the actual point of wetness while precluding leakage of the moisture at the point of visual indication.
Another object of this invention is to provide a method for indicating a condition of moisture at a point removed from the actual point of moisture while preventing such moisture from leaking onto the surrounding areas adjacent to the point of viewing.
The foregoing has outlined some of the more pertinent objects of the invention. These objects should be construed to be merely illustrative of some of the more prominent features and applications of the intended invention. Many other beneficial results can be attained by applying the disclosed invention in a different manner or modifying the invention within the scope of the disclosure. Accordingly, other objects and a fuller understanding of the invention may be had by referring to the summary of the invention and the detailed description of the preferred embodiment in addition to the scope of the invention defined by the claims taken in conjunction with the accompanying drawings.